/usr/include/bullet/BulletCollision/CollisionShapes/ is in libbullet-dev 2.81-rev2613+dfsg2-1.
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/usr/include/bullet/BulletCollision/CollisionShapes/btBox2dShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btBoxShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btBvhTriangleMeshShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btCapsuleShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btCollisionMargin.h
/usr/include/bullet/BulletCollision/CollisionShapes/btCollisionShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btCompoundShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConcaveShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConeShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvex2dShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexHullShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexInternalShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexPointCloudShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexPolyhedron.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btConvexTriangleMeshShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btCylinderShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btEmptyShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btMaterial.h
/usr/include/bullet/BulletCollision/CollisionShapes/btMinkowskiSumShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btMultiSphereShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btMultimaterialTriangleMeshShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btOptimizedBvh.h
/usr/include/bullet/BulletCollision/CollisionShapes/btPolyhedralConvexShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btScaledBvhTriangleMeshShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btShapeHull.h
/usr/include/bullet/BulletCollision/CollisionShapes/btSphereShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btStaticPlaneShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btStridingMeshInterface.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTetrahedronShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleBuffer.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleCallback.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleIndexVertexArray.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleIndexVertexMaterialArray.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleInfoMap.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleMesh.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleMeshShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btTriangleShape.h
/usr/include/bullet/BulletCollision/CollisionShapes/btUniformScalingShape.h